JPH0322055Y2 - - Google Patents

Description

[Detailed description of the invention] a. Industrial application field The present invention relates to a load-responsive braking hydraulic pressure control device that reduces the output hydraulic pressure of a master cylinder at a predetermined rate corresponding to the loaded load. Hydraulic pressure prevents the plunger that opens and closes the installed on-off valve and the stem that applies a pressing force to the plunger according to the load from colliding with each other during brake operation and causing abnormal noise. Regarding a control device.

b. Prior Art This type of hydraulic pressure control device is installed in the middle of the hydraulic passage from the brake master cylinder to the rear wheel cylinder, and when the braking force is low at the beginning of braking, it applies the same braking force to the front wheels to the rear wheels. When the braking force exceeds a predetermined value, a smaller braking force is applied to the rear wheels than the front wheels, thereby preventing the rear wheels from locking. In addition, in vehicles such as trucks, the amount of braking force that causes the rear wheels to lock differs depending on the size of the live load. is configured to be large and to be small when it is small.

More specifically, as shown in FIG. 2, the hydraulic control device 1 is fixed to a chassis frame 2, and the tip of a load detection lever 3 extending horizontally is connected to an axle-side bracket 5 via a tension spring 4. ing. Note that the load detection lever 3 is arranged to be movable up and down about a fulcrum 9.

A vertically slidable plunger 6 is housed inside the hydraulic pressure control device 1, and an input pressure chamber 7 and an output pressure chamber 8 are formed around the plunger 6. The input pressure chamber 7 is connected to a brake master cylinder (not shown) by a conduit 11, and the output pressure chamber 8 is connected to a rear wheel cylinder (not shown) by a conduit 12.

A valve chamber 13 is formed above the output pressure chamber 8 , and the valve chamber 13 and the input pressure chamber 7 are communicated with each other by a communication passage 14 . In addition, the valve chamber 13 and the output pressure chamber 8
are communicated by the valve seat hole 15, and this valve seat hole 15
is opened and closed by a ball valve 16.

The upper end 6a of the plunger 6 is inserted into the valve seat hole 15, and normally pushes up the ball valve 16 against the spring 17 to open the valve seat hole 15. Further, the lower end 6b of the plunger 6 is in contact with a stem 18 that is integral with the load detection lever 3, and the plunger 6 is pushed up by the force of the tension spring 4. Note that the step portion 6c formed at the upper end of the plunger 6 is normally in contact with the end wall 19 of the output pressure chamber 8, and the pushing up force of the plunger 6 is supported by this end wall 19.

A small pressure receiving surface 22 and a large pressure receiving surface 23 are formed on the outer peripheral surface of the plunger 6 facing the input pressure chamber 7 and the output pressure chamber 8, and when the brake operating hydraulic pressure is supplied to the input pressure chamber 7, the pressure receiving area difference is The plunger 6 is pressed downward.

The conventional hydraulic pressure control device 1 is generally configured as described above, and when brake operating hydraulic pressure is supplied to the input pressure chamber 7, this hydraulic pressure is transmitted through the communication passage 14, the valve chamber 13, the valve seat hole 15, and the output pressure chamber 7. It is supplied to the rear wheel cylinder through the pressure chamber 8. Further, the same hydraulic pressure as that of the input pressure chamber 7 is supplied to the front wheel cylinder through a hydraulic pressure passage of a separate system.

The plunger 6 is pushed down against the tension spring 4 due to the area difference between the small pressure receiving surface 22 and the large pressure receiving surface 23.
Until the ball valve 16 is closed, the same hydraulic pressure as the front wheel cylinder is supplied to the rear wheel cylinder. However, when the hydraulic pressure in the input pressure chamber 7 rises to a certain extent, the ball valve 16 closes, and from then on, the hydraulic pressure in the input pressure chamber 7 increases, the plunger 6 rises, the ball valve 16 opens, the plunger 6 descends, and so on. The plunger 6 moves up and down by a differential pressure, and as a result, the hydraulic pressure in the input pressure chamber 7 is reduced at a predetermined rate and introduced into the output pressure chamber 8.

Fig. 3 is a graph showing the pressure relationship between the input pressure chamber 7 and the output pressure chamber 8, and shows a situation in which the pressure is reduced from point A when the load is empty, and from point B when the load is loaded. ing. This is because during loading, the chassis frame 2 sinks and the tension spring 4 is stretched, resulting in an increase in the upward force acting on the plunger 6 and an increase in the input hydraulic pressure when the ball valve 16 is closed. be.

In this way, as the load increases, the magnitude of the braking force that begins to reduce the proportion of the rear wheel braking force is increased, which prevents the rear wheels from unexpectedly locking up when the vehicle is unloaded, or reduces the braking force when the vehicle is loaded. There will be no shortage of

c. Problems to be Solved by the Invention Although the conventional hydraulic pressure control device 1 operates as described above, the following problems have been pointed out with this device 1. In other words, when the load is empty, the stem 18
A gap exists between the stem 18 and the lower end 6b of the plunger 6, and therefore, when the brake is applied, the stem 18 and the lower end 6b of the plunger 6 collide with each other, producing a hammering sound due to metal-to-metal collision. This hitting sound not only impairs the quietness of the driver's seat, but in some cases, vibrations caused by this hitting sound may be propagated to the brake pedal, impairing driving comfort.

The present invention was devised in view of the above-mentioned circumstances, and its purpose is to provide a hydraulic pressure control device that can prevent abnormal noise from occurring due to collision between the stem of the load detection lever and the plunger. be.

d Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an on-off valve disposed in the hydraulic pressure passage leading from the brake master cylinder to the rear wheel cylinder, and a control valve for the output hydraulic pressure of the brake master cylinder. A load-responsive braking hydraulic pressure control device comprising: a plunger that opens and closes the opening/closing valve in response; and a stem that is integrated with a load detection lever and presses the plunger in the valve opening direction according to a live load; a cap is interposed between the cap and the stem, a cylinder is formed in either the cap or the stem, the other of the cap or the stem is slidably fitted into the cylinder, and An elastic member is interposed between the bottom surface of the cap and the tip of the other of the cap or the stem, and a spring is disposed between the cap and the stem to press the cap into contact with the plunger. There is a particular thing.

e Effect In the hydraulic control device configured as described above, even if the stem and plunger collide during brake operation, this impact force is relaxed or absorbed by the elastic member, so no abnormal noise is generated. do not have.
Further, during operation, the pressing force of the stem acts on the plunger via the elastic member as in the conventional case, and the output hydraulic pressure of the brake master cylinder is reduced at a predetermined rate and supplied to the rear wheel cylinder.

f. Example An example of the present invention will be described below based on FIG. 1. As shown in the figure, in the present invention, a synthetic resin cap 35 is slidably fitted to the stem 18. A holding hole 35a is formed in the center of the upper surface of the cap 35, and a steel ball 36 is housed and held in this holding hole 35a. on the other hand,
A spring receiving flange portion 35b is formed on the outer periphery of the upper end of the cap 35, and an auxiliary spring 27 is disposed between this flange portion 35b and the flange portion 18a on the stem 18 side. This auxiliary spring 27 is used to apply the minimum necessary upward force to the plunger 6 to open the ball valve 16 when the tension spring 4 is broken.

Further, the cap 35 is formed with a cylinder 35c that opens at the lower end.
The tip of the stem 18 is slidably fitted into the hole c. And the bottom surface 35d of this cylinder 35c
A rubber disk 37 as an elastic member is interposed between the end face 18b of the stem 18 and the end face 18b of the stem 18.

Note that the stepped portion 28a of the housing 28 and the stem 1
The spring 3 disposed between the flange portion 18a of the spring 8
1 is the first when the tension spring 4 is broken as described above.
This is for rotating the load detection lever 3 shown in the figure downward around the fulcrum 9 and fixing it to the stopper bolt 32.

The configuration of the other parts of the hydraulic pressure control device is the same as that of the conventional device shown in FIG. 2, so a description thereof will be omitted.

In the hydraulic control device constructed as described above, the cap 35 is urged upward by the urging force of the spring 27, and the cap contacts the plunger 6 via the ball 36. In this state, even if the stem 18 vibrates in the vertical direction when braking is not applied, this vibrational impact force is relaxed and absorbed by the rubber disk 37, and rattling noise between the stem 18 and the plunger 6 does not occur.

On the other hand, during braking, the pressing force of the stem 18 is applied to the rubber disk 37, the cap 35 and the ball 3.
6 acts on the plunger 6 in the same manner as before. Therefore, the output hydraulic pressure of the brake master cylinder is reduced at a predetermined rate corresponding to the cargo load and supplied to the rear wheel cylinder.

The ball 36 is used to prevent the swinging force of the stem 18 about the fulcrum 9 from acting on the plunger 6.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified in various ways. For example, although the rubber disk 37 is used as the elastic member in the above embodiment, a spring washer or the like may be used instead of the rubber disk 37. Alternatively, the lower end of the cap 35 may be made cylindrical, a hole may be formed on the stem 18 side into which this cylindrical portion is slidably inserted, and an elastic member may be disposed at the bottom of this hole. Alternatively, the ball 36 may be omitted and the lower end surface of the plunger 6 may be processed into a spherical surface so that it makes point contact with the cap 35.

g. Effects of the invention As mentioned above, in this invention, an elastic member is provided on the contact surface between the stem and the plunger, so the collision force between the stem and the plunger when the brake is applied is alleviated and absorbed by the elastic member. This prevents the generation of abnormal noises that occur in the conventional system, and improves the quietness and comfort of the driver's seat. Moreover, since the elastic member is housed in the cylinder and force is transmitted through the entire elastic member, the elastic member has high durability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the vicinity of the lower end of a plunger of a load-responsive braking hydraulic pressure control device according to an embodiment of the present invention. Further, FIG. 2 is a longitudinal sectional view of a conventional load-responsive braking hydraulic pressure control device, and FIG. 3 is a graph diagram of the input/output hydraulic pressure relationship of the same device. 3...Load detection lever, 6...Plunger, 1
6...Ball valve (on/off valve), 18...Stem, 1
8b... End face, 35... Cap, 35a... Holding, 35b... Flange portion, 35c... Cylinder, 35d... Bottom surface, 37... Rubber disk (elastic member).

Claims (1)

[Scope of utility model registration request] An on-off valve disposed in the hydraulic pressure passage leading from the brake master cylinder to the rear wheel cylinder, a plunger that opens and closes the on-off valve in response to the output hydraulic pressure of the brake master cylinder, and a load detection lever integrated with each other to detect the load. A load-responsive braking hydraulic pressure control device comprising a stem that presses the plunger in the valve opening direction in response to the pressure, wherein a cap is interposed between the plunger and the stem, and either the cap or the stem a cylinder is formed in the cylinder, either the cap or the stem is slidably fitted into the cylinder, and an elastic member is provided between the bottom surface of the cylinder and the tip of the other of the cap or the stem. A load-responsive braking hydraulic pressure control device characterized in that a spring is interposed between the cap and the stem to press the cap into contact with the plunger.